The projects were devised as part of a 2015 action plan to treat and prevent water pollution, and covered 325 contaminated groundwater sites across the country. A total of 343 contaminated sites had been identified, meaning that 95 per cent had drawn up plans to bring water quality up to required standards.

Large amounts of China's water have been rendered unusable as a result of poorly regulated industrial expansion, overmining and the uncontrolled use of pesticides and fertilisers.

China grades its water in six bands, with the lowest "below grade 5" considered unusable even for industrial or irrigation purposes, and described as "black and stinky".

Of 2,100 "black and stinky" sites identified, 44.1 per cent had completed treatment projects in the first half of the year, the ministry said, adding that the provinces of Hebei, Shanxi, Liaoning and Anhui had fallen behind.